The glycemic load might be a better guide to healthy eating than the glycemic index
What should we believe? The Internet bombards us with so many facts, ideas, opinions and outright lies, it’s hard to make out the signal from the noise.
Dr. Davis in his book Wheat Belly makes a lot of noise about wheat. He calls it a blight and a poison and says no-one should eat it, not just the 6% of us who are gluten intolerant. But many of his statements are misleading.
Example… Davis is often quoted as saying: “The glycemic index proves eating bread is worse than eating straight sugar.” Nonsense. And I’m not sure he does say this, exactly. But many have dropped wheat from their menues, on his advice.
The glycemic index (GI) measures how quickly a food is changed to the sugar that fuels the body. The GI of glucose (a simple sugar) is 100. The GIs of ALL OTHER FOODS are compared with that of glucose. Only some other kinds of sugar have GIs higher than 100.
Foods with a high GI can raise our blood-sugars rapidly. Sugar highs stress the systems that process it. Over time the systems break. That triggers things like diabetes, high blood pressure and some cancers. A GI over 55 is high.
But it’s the glycemic load (GL) that we should pay the most attention to. A GL of 10 or less is low. Foods with a low GL do not raise your blood sugar excessively, even if they have a high GI.
The glycemic load takes into account the amount of carbs in a serving. A food like watermelon has a high glycemic index (72)… but there’s not that many carbs in one serving. So it has a low glycemic load (4). Serving size counts!
A glycemic load (GL) of 20 or more is too high for good health. If you eat more than the serving size shown in the table, you have to multiply the GL by the same amount. Example: The serving size for table sugar is 30 grams (about 2 tablespoons), for a GL of 21 – high. But a 20 ounce bottle of Coke has 65 grams of sugar. Its glycemic load is more than 45 – very high.
Are you still with me?
Sweet but wise watermelon owl doesn’t raise blood sugar excessively, thanks to a low GL
Davis uses numbers to convince us to follow a gluten-free diet. So we need to look at numbers, too, to decide for ourselves whether we need to give up wheat. Check out this table from Harvard Medical School. I’ve taken some numbers from it for sugar and various foods made from flour:
- GI = the glycemic index, where glucose = 100
- SS = the serving size, in grams
- GL = the glycemic load.
|Sugar, glucose||100||30 (2 tablespoons)||75|
|Table sugar, sucrose and fructose||68||30 (2 tablespoons)||21|
|Bagel, white, frozen||72||70||10|
|Baguette, white, plain||95||30||15|
|White wheat flour bread||71||30||10|
|Wonder™ bread, average||73||30||10|
|Whole wheat bread, average||71||30||9|
|100% Whole Grain™ bread (Natural Ovens)||51||30||7|
|Pita bread, white||68||30||10|
What do we see from this table?
Glucose has a higher glycemic index (100) AND a higher glycemic load (75) than any food made from flour.
Table sugar is made up of two sugars. Its sucrose converts quickly to simple sugar but its fructose takes longer to break down. So the GI of table sugar is lower than that of glucose and breads made from refined flours. Table sugar has a higher glycemic load, though, than the breads.
One serving of baguette made from refined white flour has a high glycemic index (95), nearly the same as glucose, but a lower glycemic load (15) than glucose or table sugar. Both these figures exceed the healthy range (above 55 and 10).
But look at whole-grain bread. Its glycemic index is lower than for glucose or table sugar (51) and its glycemic load is the lowest in the table (7). Wheat tortilla has healthier numbers (30 and 8) than its gluten-free counterpart, the corn tortilla (52 and 12). These wheat foods fall in the healthy range (below 55 and 10).
What did Davis say about GI and wheat?
1) “Whole wheat bread has a higher glycemic index than a Mars Bar.”
Davis is right. But did he mention Mars Bar has an unhealthy glycemic load?
The glycemic index compares how blood-sugar levels respond to 50 grams of available carbohydrate in the food. The GI for 50 grams of glucose, all of which is available carbs, is 100.
To get 50 grams of carbs from whole-wheat bread, you need to eat 4 slices. For 50 grams of carbs from a Mars Bar, you need only 2.5 ounces or about 1 bar. So the volume of food differs. Also, the kinds of carbs differ. Higher fat content in the bar impedes digestion of its starch. Nuts and chocolate in the bar have a low glycemic index, which lowers the glycemic index of the bar. Because the calories and nutrients are so different, it’s misleading for Davis to compare the GIs of these two foods. The comparative load is more meaningful.
2) “Whole-wheat bread has the same GI as white bread.”
Davis is right. Check the table, above. All the breads except whole-grain bread have a glycemic index of more than 70. But the GI of the whole-grain is in the healthy range.
Now, check out their glycemic loads. Whole-grain bread is 3 points lower (nearly a third better) than white bread and comes in at less than 10. So… whole-grain bread is a healthy choice, in moderation.
It’s smart to check up on the glycemic loads of the foods you eat regularly. If the GL of one serving is over 10, consider making a change.
Try making a super delicious recipe for sweet potato scones from whole-grain flour mixed with some refined white flour, to ensure lightness. They’re so airy, you’ll be in seventh heaven!
- For a point-by-point analysis of Davis’s claims, check out this scientific analysis from St. Catherine University, St. Paul, MN. This same review looked at hundreds of studies on health effects of refined flour, as well as whole wheat and whole grain flours. The conclusion: Unless your doctor tells you you’re gluten intolerant, moderate use of whole-grain flour in a daily meal plan has no proven ill-effects on your long-term health.
- Photo of the wise owl is from Daily Picks and Flicks.
- How many people have gluten insensitivity? See how many people have been diagnosed with gluten sensitivity, intolerance and celiac disease.
- Wheat is not satan… but watch out for those little sugar devils See what Davis had to say about wheat and obesity and learn why most healthy people can keep whole-grain flour in their meal plan.